Alcohol misuse in the United States is a large and far reaching problem. Most individuals do not seek alcohol treatment on their own. Because those who misuse alcohol frequently sustain and need care for injuries, health care professionals have an opportunity to screen and provide brief intervention services. Research over the past 20 years has demonstrated that screening and brief interventions (SBI) for alcohol can reduce use, injury recidivism, and adverse driving events. Support for brief alcohol interventions is such that accreditation standards for Level-1 trauma centers require SBI service delivery. However, SBI does not appear to be effective with all injured patients. A number of SBI trials have not demonstrated significant reductions in alcohol use or other injury risk behaviors. Furthermore, the delivery of SBI services is largely unfunded, and providers are left to screen and provide interventions without compensation. To better utilize SBI resources, one approach could be to target interventions to those who are most likely to make positive changes after receiving interventions. In order to apply a targeted approach for SBI with injured patients who misuse alcohol, knowing which patients respond best is critical. However, a limited understanding exists within the field regarding which injured patients benefit the most from SBI. To identify which injured patients in a Level-1 trauma center respond best to SBI, three separate analyses will be undertaken in this dissertation. Analyses one and two will be conducted using data from a RCT conducted in a Level-1 trauma center. The first analysis will use latent class analysis to identify probabilistic patient profiles or classes based on past injury-related risk behaviors. Benefit from the brief intervention will be measured by which injury-related risk profile experienced the greatest reductions in post-intervention alcohol use. The second analysis will analyze the longitudinal injury-related risk behavior profile changes experienced by patients in the year following the receipt of a brief alcohol intervention. Latent transition analysis will be used to model the longitudinal transitions individuals experience from their baseline injury-related risk subgroups into other subgroups across time. Analysis three will be conducted in a similar but separate dataset from another RCT conducted in a Level-1 trauma center. This third analysis will replicate the model(s) developed in Aim 1 and/or 2. The purpose of replicating findings from Aim 1 and/or Aim 2 in a separate dataset is to determine whether the established model(s) can be supported in a second population. This dissertation will add to the limited evidence in the health services field with respect to which traumatically injured patients respond best to SBI. Possessing a greater knowledge of which injured patients respond best to SBI will increase the ability of policymakers, health care administrators, and clinicians to make potentially necessary changes to improve the effectiveness and efficiency of medical centers delivering SBI services to injured patients. PUBLIC HEALTH RELEVANCE: Alcohol misuse is the primary risk factor for injury in the United States. Health care providers have excellent opportunities to deliver alcohol interventions to individuals admitted to health care facilities for injury treatment. Understanding which injured patients respond best to alcohol interventions delivered in health care settings is critical in ordr to effectively and efficiently utilize scarce behavioral health services, decrease alcohol misuse, and reduce future injury.